A unified model for predicting flow patterns in the pipeline-riser system is essential for the flow assurance of offshore oil and gas pipelines. This paper uses the visual images and pressure signals to obtain the internal correlation and the transition boundaries of the overall and local flow patterns in a 46 mm ID, 1722 m long pipeline S-shaped riser system. The flow pattern map with industrial parameters is plotted, and a fast identification method for unstable flow is proposed based on the differential pressure signal of the riser. The mapping relationship between the overall flow pattern divided by the pressure signals and the local flow pattern distinguished by the visual images is established. The transition mechanism dominated by the liquid phase is whether the gas in the downward-inclined pipeline accelerates after entering the riser base, and the transition mechanism dominated by the gas phase is whether the gas can penetrate the liquid in the riser so that the gas does not accumulate in the downward-inclined pipeline. A unified mechanistic model is proposed for predicting the overall flow pattern transition boundaries in pipeline-riser systems. The model results show a good agreement with 24 kinds of flow pattern maps under various pipeline structures, fluid properties, and separator pressures.

中文翻译：

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管道立管系统整体和局部流型的实验研究和预测

预测管道-立管系统中流动模式的统一模型对于海上石油和天然气管道的流动保证至关重要。本文利用视觉图像和压力信号来获取内径46 mm、长1 722 m的S形立管系统整体和局部流型的内部相关性和过渡边界。绘制了带有工业参数的流型图，提出了一种基于立管压差信号的不稳定流量快速识别方法。建立了由压力信号划分的整体流型与由视觉图像区分的局部流型之间的映射关系。液相主导的转变机制是下倾管道中的气体进入立管底座后是否加速，气相主导的转变机制是气体能否穿透立管内的液体，从而使气体进入立管底部。不会积聚在向下倾斜的管道中。提出了一个统一的机械模型来预测管道-立管系统中的整体流型转变边界。模型结果与不同管道结构、流体性质和分离器压力下的24种流型图吻合良好。